Expression of serum amyloid A transcripts in human bone tissues, differentiated osteoblast‐like stem cells and human osteosarcoma cell lines

Serum amyloid A (SAA) is a major acute-phase protein in humans, and elevated plasma levels represent a risk factor for cardiovascular diseases. SAA was thought to be produced by hepatocytes only in response to inflammatory stimuli; moreover, recent studies have shown that adipose tissue can secrete several proinflammatory factors. Therefore, we investigated whether cells in adipose tissue can synthesize SAA in response to inflammatory stimuli. Adipocytes and preadipocytes isolated from abdominal adipose tissue were incubated with IL-1, IL-6, TNF-α, LPS, or resistin at different concentrations. After 48 hours, the supernatants were analyzed by ELISAs for human SAA. Preadipocytes did not show any production in SAA. In contrast, in adipocytes, incubation with TNF-α led to a significant increase in SAA production, peaking after LPS or resistin (∼3 times greater vs unstimulated adipocytes). The greatest increase in SAA occurred with all stimuli combined (∼5 times greater vs control cells). Subsequently, we investigated whether treatment with some drugs could modulate SAA production in adipocytes, and observed that fluvastatin led to a significant inhibition of SAA release, whereas a larger modulation of SAA release was observed after treatment with troglitazone or aspirin. These results show for the first time that human adipocytes, and not preadipocytes, can produce SAA in response to inflammatory cytokines and that this process can be modulated.

show abstract

“…Interestingly, these inflammatory molecules are the ones responsible for both the hepatic and extrahepatic production of SAA (8)(9)(10).…”

Section: Discussionmentioning

confidence: 99%

Production of Serum Amyloid a in Response to Inflammatory Cytokines by Human Adipocytes

et al. 2010

View full text Add to dashboard Cite

show abstract

“…RT-PCR was performed using an RT-PCR kit according to the manufacturer's protocol (Invitrogen). DNase-treated RNA (1 lg) was used in the reverse transcription with random hexamers and oligo(dT) [12][13][14][15][16][17][18] as the extension primer. PCR was performed by denaturing at 94°C for 2 min, followed by incubation at 94°C for 15 s and 68°C for 1 min for 40 cycles.…”

Section: Isolation Of Rna and Rt-pcrmentioning

confidence: 99%

SAF‐3, a novel splice variant of the SAF‐1/MAZ/Pur‐1 family, is expressed during inflammation

et al. 2009

Self Cite

View full text Add to dashboard Cite

The Cys2His2‐type zinc finger transcription factor serum amyloid A activating factor 1 [SAF‐1, also known as MAZ (myc‐associated zinc finger protein) or Pur‐1 (purine binding factor‐1)] plays an important role in regulation of a variety of inflammation‐responsive genes. An SAF‐2 splice variant acting as a negative regulator of SAF‐1 was identified previously, and the present study reports the identification of a novel SAF‐3 splice variant that is expressed during inflammation. SAF‐3 mRNA, isolated from a cDNA library produced from IL‐1β‐induced cells, originates from a previously unknown first coding exon, and thereby contains a unique N‐terminal domain but shares the same six zinc finger DNA‐binding domains as present in SAF‐1. In addition, a negatively functioning domain present at the N‐terminus of SAF‐1 and SAF‐2 is spliced out in SAF‐3. The expression of SAF‐3 is very low in normal tissues and in cells grown under normal conditions. However, RT‐PCR analysis of mRNAs from cytokine and growth factor‐induced cells as well of mRNAs isolated from several diseased tissues revealed abundant expression of SAF‐3. The transactivation potential of SAF‐3 is much greater than that of the predominantly expressed splice variant SAF‐1. These findings show that transcriptional regulation of downstream inflammation‐responsive genes by SAF/MAZ/Pur‐1 is likely to be more complex than previously assumed. In addition, we show that SAF‐3 expression initiates from an upstream novel promoter. This is the first report of the existence of multiple promoters regulating expression of the SAF/MAZ/Pur‐1 family of proteins.

show abstract

“…In our previous study, we demonstrated that the amount of circulating SAA is higher in the plasma of patients with osteosarcoma relative to that in the plasma of patients with benign osteochondroma (7). Studies have also shown that SAA is expressed in bone tissues and osteosarcoma cell lines (25) and that the amounts of SAA in the sera are associated with the relapse of osteosarcoma (26). These results further implicate the importance of this protein in the biology of osteosarcoma.…”

Section: Discussionmentioning

confidence: 60%

Plasma proteome predicts chemotherapy response in osteosarcoma patients

Dang

Shen

et al. 2011

Oncol Rep

View full text Add to dashboard Cite

Abstract. Osteosarcoma is the most common malignant bone tumor that affects hundreds of children and young adults every year. The major prognostic factor in patients with localized osteosarcoma is the development of resistance towards preoperative chemotherapy. However, modifications of postoperative chemotherapy based on the histological response have not significantly improved the outcome of patients. Thus, it would be of tremendous clinical value if the poor responders could be identified at the time of diagnosis, so that ineffective therapy can be prevented and intensified or alternative therapy could be provided to improve their outcome. We hypothesized that plasma proteomic profiles could be used to distinguish good from poor responders prior to the start of treatment. In order to test this hypothesis, we analyzed the proteomic profiles in two sets of plasma samples (n=54) from osteosarcoma patients collected before (n=27) and after (n=27) pre-operative chemotherapy. Using a linear support vector machine algorithm and external leave-one-out cross validation, we developed two classifiers that classified good and poor responders with an equal accuracy of 85% (p<0.01 after 5000 permutations) in both sets of plasma samples. In order to understand the biological basis of the classifiers, we further identified and validated two plasma proteins, serum amyloid protein A and transthyretin, in the classifiers. Our results suggest that plasma proteomic profiles can predict chemotherapy response before treatment as accurately as after treatment. Our study could lead to the development of a simple blood test that can predict chemotherapy response in osteosarcoma patients. Since the two identified proteins are involved in innate immunity, our findings are corroborated by the notion that boosting the innate immunity in conjunction with chemotherapy, achieves a better anti-tumor activity, thus improving the overall survival of osteosarcoma patients. IntroductionOsteosarcoma is a primary malignant bone tumor bone arising from primitive bone-forming mesenchymal cells and is characterized by the production of osteoid material (1). It is a common malignant bone tumor occuring in children and accounts for ~60% of malignant bone tumors which occur during the first two decades of life (2). Since the 1970s, the accepted standard of care for osteosarcoma involves four steps: Diagnosis by an initial biopsy, pre-operative chemotherapy, definitive surgery to resect the tumor, and postoperative chemotherapy (Fig. 1). Besides facilitating limbsparing procedures by shrinking the tumor, pre-operative chemotherapy can theoretically be used as an in vivo indicator of the chemosensitivity of an individual tumor, thus providing a guide for the customization of post-operative chemotherapy. However, the strategy of pre-operative chemotherapy has not improved disease-free survival for patients with osteosarcoma. Despite a number of multi-institutional clinical trials of pre-operative chemotherapy in both Europe and North America, the overall su...

show abstract

Expression of serum amyloid A transcripts in human bone tissues, differentiated osteoblast‐like stem cells and human osteosarcoma cell lines

Cited by 41 publications

References 51 publications

Production of Serum Amyloid a in Response to Inflammatory Cytokines by Human Adipocytes

Production of Serum Amyloid a in Response to Inflammatory Cytokines by Human Adipocytes

SAF‐3, a novel splice variant of the SAF‐1/MAZ/Pur‐1 family, is expressed during inflammation

Plasma proteome predicts chemotherapy response in osteosarcoma patients

Contact Info

Product

Resources

About